Question for Runners - Tightness/Pain in Hip

OK, so I am going to throw a lot of facts out first to provide context:

1. A runner I am not, I am however, an avid hiker
2. Flat Feet
3. Narrow Feet
4. Custom Orthotics
5. Nike Running Shoe
6. On treadmill 3-4 times a week for 45-60m
7. I stretch legs and lower back for 5 minutes before the treadmill, especially hips and glutes
8. I walk at a slightly elevated pace for the first 5 minutes on the treadmill to loosen up.
9. I walk at a regular pace for the last 5 minutes on the treadmill to cool down.
10. I stretch legs and lower back for 5 minutes after the treadmill, especially hips and glutes
11. One day a week, I strength train legs
12. 18 lbs down from when I started this routine but still about 50lbs overweight

I am a regular hiker, but suck at running - to the point that I don't try it. I get shin splints, strange sharp pains in legs, and my arch hurts like a mother, and I suck air 30 seconds into it. However, as a personal goal, I wanted to see if I could slowly get myself to a 10 minute mile and actually jog. (A hiker, unencumbered will walk a mile in roughly 20 minutes).

Slowly over the past 1.5-2 months I am slowly ratcheting up speed within a interval training - for example, today:

1. 5 minutes warming up at 3.0
2. 5 minutes at 3.7
3. 10 minutes at 4.2 (This is at the top end of my walking speed and kinda kicks my butt)
4. 5 minutes at 3.5
5. 10 minutes at 4.2 (This is at the top end of my walking speed and kinda kicks my butt)
6. 5 minutes at 3.5
7. 5 minutes at 5.0 (First time I have jogged comfortably for five minutes, EVER)
8. 5 minutes cool down at 3.5

This is compared to a month ago when I walked 40 minutes at 3.0 comfortably.


Over the past 2 months I have been doing this I have been confused by tightness and pain in various parts of my legs. I think a lot of it is the longer stride I am taking walking at high speed. But as I get more accustomed to it, the strange tightness and pain goes away (like the arch of my foot or shin splints).

However, I am consistently really damn tight where my hip would attach to my pelvis. If I held my arms down at my side, the point is almost exactly where my wrist is. I stretch, I have had massages to loosen it up (which has helped A LOT), I have been taking ostio-biflex to help with joint health.

But I am still tight and sore there, have been for 2 months since I started to ratchet up my walking routine. So far, no pain. But the uncomfortableness has me concerned.

So, I apologize for all the back story but:
1) Has anyone else experienced this?
2) I'm thinking this is just due to the unusual routine and that making my body do things it has never done at 40 is what I am feeling. Your thoughts.

Thanks in advance for your help.